It is generally known to secure drain conduits at the injector-nozzles with standard annular parts (produced in accordance with German Industrial Standard DIN 7622), and with standard hollow fasteners (produced according to German Industrial Standard DIN 7632). In certain situations, the annular part is in the form of a double or duplex annular part with a short connecting conduit for the inlet section of the duct and a short connecting conduit for the outlet section of the conduit. However, when space is restricted, the inlet and outlet have to be approximately axis-parallel to the injector-nozzle holder. In such situations duplex annular parts with oppositely arranged connections cannot be used. To avoid this, prefabricated annular parts can be provided having two connections which are arranged in V-form. However, this would be very expensive and is, accordingly, not desirable.